Phase shifting apparatus



April 1951 E. H. B. BARTELINK 2,548,855

PHASE SHIFTING APPARATUS Filed Dec. 11, 1946 Fig. l

RF 2 WAVE SOURCE 7 UTILIZATION PHASE SHIFTING DEVICE AMPLIFIER Inventor: Evebhard l-LB. Bartelink,

His Attorney.

Patented Apr. 17, 1951 Everhard H, B, Bartelink, Bronxville, N. Y. assignor to General Electric Gompan y, a corporation of New 'York Application December 11, 1946, Serial No. 715,427

'9 Claims. (01. 323{1] ;9)

My invention relates to phase shifting apparatus and particularly to such apparatusfor use at radio frequencies.

In many types of high frequency apparatus it is necessary to provide some device for shifting the phase of signals over a wide range. This is the case, for example, in phase modulation systems. For many applications it would be desirable thatsuchphase shifting devices be capable of operating over .a range of three hundred and sixty degrees .and be calibrated over that range. Furthermore, the adjustment of these phase shifting devices should not vary their input loading with variations of phase at .the output. Accordingly, it is an object of my invention to provide .an improved phase, shifting apparatus which ,i suitable Iornperationat radio frequencies.

It is another object of my invention to provide a phase shifting apparatus including an improved arrangement for adjusting "the amount of jitselffhowever, both as to its organization and methodof operation, "together with -further objects and advantages thereof may 'best be understood by'reference to the following description taken in connection with the accompanying "drawing in which'Fig. 1 represents an'embodb ment of my invention and Fig. 2 is a circuit dia- "gram of '-;one of the phase shifting ampli fiers employed inFig. 1.

"The phase shifting apparatus "illustrated in "Fig. 1 is arranged to provide any desired phase difierence from zero to three hundred and sixty degrees 'betweenihighfrequency signals -=supplied :from a source tandthe output'voltage-ofthe apparatus impressed on a utilization -device 2. "The-phase shifting-apparatus includes two parallelbranch paths 3 and 4. The path fs-includes a phase shifting amplifier '5 "the output of which is impressed on a control electrode-6 of an-electron discharge device 1. "The "path *4--'includesa ninety -degree phase I shifting J apparatus 8 and a phase shifting amplifier 9 connected to the output of "the device "8 and havingits output 'con- 'nected' toa control electrode 10 of an electron discharge 'device I I. Theelectromdischargedevices! and. include anodes l2 and I3, respectively, connected to a common source'of direct current; The cathodes'of the devices 1 and H indicated at [4 and I5 respectively, are'connected to gro.und through a common output resistor l6 aQrQss which th utilization device -:2 is c nnected.

The ha shifti g am fi and 9 h characteristics suchihat their output yoltage I," maybe changed from a predeterminedmaxirnum value in phase .with their input through zero-to a prgdetcrminedmaximum X51116 f n' ir n eighty degrees out 'of phase with the input. By a r i two suc am fie s S ly a s i qn ,outpu assho-w nt e ia rairi; o e plifier narmeit in ui n nety d g bu 0 Phase with res ect t e inputo he other, t s 11 0 .Sible to provide any desired phase --rel a-tierisl 1ip b t e the in t sig up l d r' h source ,I and the resultant output yoltageacro'ss the resistance l6. The shi fting of the amplitude, and thereby the phas 0f h 'resn n w m across the resistor 16.01: the outputs of the two ampl fiersgis iie ied b a as e rc t" m- 26 prising a'battery or pther suitable direct current 'source 1. and Wo circular resistors 19 and 120' ,connectedcacross the ,Sogir'ce inparallel for bia fing the amplifier 5. and; 9 respectively. --'-Ihe normal bias of the amplifiers is providedbya bat- 3Q te y .o othe sour e 1 gonng d' stiv t idpoin p i hegbat e 11 andl=r 1 Ther ..sistor l 9 is p;rovidedlwith a rotatable,contactgr z l and t e r isto :2." .withxa sim la semest :2?- .T ese ontactorsare morabl .o, re p; .f rences-ofthe resistors .I3Iandi0eudar8 se l t together by' a suitable mechanical cpupligigifi so that the phases of the outputs of the amplifiers 5 and 9 are simultaneously adjusted in such a manner as to provide'gacontinuous phase shift 40 from zero to three hundred and sixty degrees as ;the 'd evice23 is adjusted over its range. It-Will fbe observed that the amplifier control voltage' is increased asecontactof-ZI or "22' 'I'rioves ;upw-ard iromeither horizontal position, and that it is decrease asthetenfi tor:m dwnwa fiw isuchrositio plt will reunders cq tha the a ustm n of the .itwo res stors flifian 72 .11 et i i n dt h amplitudes of "the outp ,ts 9f the twoampliiiers 5 and 9 which are necessary to provide the required resultant for any desired output of the apparatus across the resistance l6. It will be evident, for example, that the output of one of the anipl ifiersb5 and 9 'must' beat a maximum value whenever th'e outputcf the other: is at zero.

' 3 Thus, as shown in Fig. 1, the contactors 2| and 22 are mechanically maintained at positions 90 degrees from each other on the circular resistors 19 and 20, respectively. In the particular contactor positions illustrated, contactor 2| has maximum control voltage applied thereto with respect to ground, while contactor 22 has only the normal voltage of battery l8a applied thereto. If contactors 2| and 22 are now rotated 90 degrees clockwise, contactor 2| will have only the normal voltage and contactor 22 will have maximum control voltage; and so on. The mechanical gauging device necessary to secure this operation forms no part of the present invention and in order to avoid complication of the drawing the details of such device have not been illustrated. i i

It will readily be understood by those skilled in the art that a gain control device may be desirable to secure amplitude correction and that such correction may be applied to the first electron discharge device in each of the amplifiers 5 and 9. I

The manner in which the amplifiers 5 and 9 operate to provide the characteristic described above will be understood in the following description of the circuit of the amplifier 5 as illustrated in Fig. 2, it being understood that the amplifier 9 is of the same construction. The amplifier 5 includes first and second stage electron discharge devices 23 and 24, respectively. The input signal from the source I is impressed on a control electrode 25 of the device 23 through a coupling capacitor 26 and across a grid resistance 21'. Electron discharge device 23 includes a cathode 28 connected to ground through a biasing resistor 29 and an anode 30 connected to a suitable source of direct current through a resistance 3|. The device 24 similarly includes a cathode 32, a biasing resistor 33 and an anode 34 connected to the source through a resistance 35. The output of the device 23 is coupled through a capacitor 36 and across a resistance 31 to a control electrode 38 of the device 24. In order to secure the required characteristic, a-feedback path is provided between the anode 34 of the device 24 and v,the ,control electrode 38, this path comprising a .;resistance 39 connected between the anode 34 and the anode 3|].

It will be recognized that'this circuit provides negative or degenerative feedback and it can be shown that, if the feedback and plate resistors are designed so that they constitute a pure resistance .and are not frequency responsive, the overall gain of the amplifier is proportional to the quantity 7 where gmz is the mutual conductance of the second stage electron discharge device and RF is the value feedback resistor. At the higher frequencies it maybe found necessary to employ.

Considered another way, the output signalvoltage at the connection joint between anode 34 and load resistor 35 will be zero when the forward of a screen electrode or grid 42.

voltage gain through stage" 23 and resistor 39 to this point is exactly balanced by the backward, or negative, voltage gain through stage 24 to thispoint. Thus, the over-all amplifier gain may be made zero at a finite value of mutual conductance gm: of the second stage 24; and the over-all gain may be increased either in-phase or out-of-phase with the input voltage by varying gm from this value. By increasing 91112 the output voltage increases in amplitude in phase with the input, andv by decreasing one the output voltage is made to increase in amplitude one hundred and eighty degrees out of phase with the input voltage. The adjustment of the mutual conductance of the second stage electron discharge device 24 to effect this variation in amplitude and phase may be accomplished, for example, by adjusting the bias The resistance H! has been shown connected across a by-pass capacitor 43. As the contactor 2| is shifted over the resistor IS, the direct current bias on the electron discharge device 24 is changed to vary the mutual conductance of the device and thereby selectively adjust the phase and amplitude of the output voltage. The output of the amplifier shown in Fig. 2 is coupled to the control electrode 6 of the output device I through a capacitor 44.

When the circuits of the amplifiers 5 and 9 are arranged as shown in Fig. 2 to provide the characteristic just described, the phase of the output voltage may be varied by adjusting the biasing resistors 19 and 20 without change in the loading of the input circuits of the amplifier, and the phase of the output voltage across the resistance l6 of the phase shifting apparatus may be adjusted through it entire range without variation of the loading of the input circuit of the apparatus.

From the foregoing, it is readily apparent that I have provided a simple and easily adjusted phase shifting apparatus for securing differences in phase between the output and input voltages over a range of three hundred and sixty degrees.

Furthermore, since the characteristic of the phase shifting amplifiers are secured by providing circuits which are substantially purely resistive, the phase shifting apparatus may be 01)- erated over a wide range of frequencies.

While I have described a specific embodiment of my invention, other arrangements will occur to those skilled in the art. I do not, therefore, desire my invention to be limited to the particular construction illustrated and described and'I intend by the appended claims to cover all .embodiments within the spirit and scope of my invention.

What I claim as newand desire to secure by Letters Patent of the United States, is: j

l. A phase shifting apparatus comprising a pair of two-stage electronic amplifiers, means for applying wave energy to the input of said apparatus, means for impressing the wave energy on the input of one of said amplifiers in phaseand on the input of the other of said amplifiers ninety degrees out of phase, the second stage of each of said amplifiers comprising an electron discharge device having an anode and a cathode andla control electrode, a feedback network between said anode and said control electrode, individual gain control means for varying the mutual conductance of each of said devices, whereby the output voltage of each amplifier may be varied in amplitude from a maximum value in phase with the input voltage through zero to a mai imum value one hundred and eighty degrees out or pa e with the input voltage, a common unicontrol means for simultaneously varying the adjustments of both said gain control means in a predetermined manner, the output. voltage or" either amplifier being zero when the output of other amplifier is a maximum, and means for combining the outputs of said amplifiers to secure a resultant output voltage of any desired phase difference withrespect to the input voltage of said apparatus.

-2. phase shifting apparatus comprising a pair of two-"stage electronic amplifiers, means for applying wave energy to the input'of said apparatus, means for impressing the wave energy on the input of one of said amplifiers in phase and on the input of the other of said amplifiers-ninety degrees out 'of phase, each of said amplifiers comprising first and second stage electron discharge devices, each of said devices having an anode and a'cathode and a control electrode, a feedbacklresistance connected between the anodes of the first and second stage devices of each amplifier, means comprising an adjustable source of unidirectional control potential for individually varying the mutual conductance of each of said second stage devices, whereby the output voltage of each amplifier may be varied in amplitude from a maximum value in phase with its input voltage through zero to a maximum value one hundred and eighty degrees out of phase With its input voltage, a common uni-control means for said sources for simultaneously varying said control potentials in a predetermined 'mannerythe output voltage of either of said amplifiers being zero when the other is a maximum, and means for combining the outputs of said amplifiers to secure a resultant output voltage of any desired phase difference with respect to the input voltage of said'apparatus.

3. A phase shifting apparatus comprising a pair of two-stage electronic amplifiers, means for applying wave energy to the input of said apparatus, means for impressing the wave energy on the input of one of said amplifiers in phase and on the input of the other of said amplifiers ninety degrees out of phase, eachlof said amplifiers comprising first and second stage electron discharge devices, each of said devices having an anode and a cathode and a control electrode, a feedback resistance connected between the anodes of the first and second stage devices of each amplifier, each of said second stage devices having a second control electrode, means including a source of direct current for biasing each of said second control electrodes, individual gain control means for changing the bias on each of said second control electrodes for varying the mutual conductance of each of said second stage devices, whereby the output voltage of each amplifier may be varied in amplitude from a maximum value in phase with its input voltage through zero to a maximum value one hundred and eighty degrees out of phase with its input voltage, a common uni-control means for simultaneously varying the adjustments of both said gain control means in a predetermined manner, the output voltage of either amplifier being zero when the output of the other amplifier is a maximum, and means for combining the outputs of said amplifiers to secure a resultant output voltage of any desired phase difference with respect to the input voltage of said apparatus.

4. A phase shifting apparatus comprising a pair of two-stage electronic amplifiers, means for applying wave energy to the input of said apparatus, means for impressing the wave energy oii theinput of oneof said amplifiers in phase and V on the input of the othero'f said amplifiers ninety degrees out of phase, the second stage of each of said amplifiers comprising an electron discharge device having an anode and a cathode and a control electrode a feedback network between said anode and saidcontrol electrode, individual predetermined manner, the output voltage of either amplifier being 'zero when the output of the other amplifier is a maximum, means including two additional electron discharge devices for combining the outputs of said amplifiers to secure a resultant output voltage of any desired phase difierence with respect to the input voltage of said apparatus, each of said additional devices having an anode and a cathode and'a control electrode, one'of said additional devices having its control electrode connected to the output of said one amplifier and the "other of "said additional devices having its control electrode connected to the outputof said'other amplifier, and an output -load impedance element common to the anode-to-cathode circuits of said additional devices. g y 1 5. A phase shifting apparatus comprising a pair of two-stage-electronic amplifiers, means for applying wave energy to the inputof saidapparatus, means for impressing the wave energy on theinput of one of :said amplifiers in phase-and on the input of the other of said amplifiers ninety degrees 'out'o'f phase, each of said amplifiers comprising first and second stage electrondischarge devices, each of said devices having an anode and a cathode and a control electrode, a feedback resistance connected between the anodes of said first and second stage devices of each amplifier, the over-all characteristic of each of said amplifiers being'such that the gain thereof is proportional to where gmz is the mutual conductance of the second stage device and R is the feedback resistance, means comprising a gain control potentiometer for individually varying the mutual conductance of each of said second stage devices, whereby the output voltage of each amplifier may be varied in amplitude from a maximum value in phase with the input voltage through zero to a maximum value one hundred and eighty degrees out of phase with the input voltage, a common uni-control means for simultaneously varying both of said potentiometers so as to vary said mutual conductances in a predetermined manner, the output voltage of either of said amplifiers being zero when the other is a maximum, and means for combining the outputs of said amplifiers to secure a resultant output voltage of any desired phase difference with respect to the input voltage of said apparatus.

6. A phase shifting apparatus comprising a pair of two-stage electronic amplifiers, means formz where gm2 is the mutual conductance of the second stage device and R is the feedback resistance, means including second control electrodes for said second stage devices and adjustable biasing means therefor for individually varying the mutual conductance of each of said second stage devices, whereby the output voltage of each amplifier may be varied in amplitude from a maximum value in phase with its input voltage through zero to a maximum value one hundred and eighty degrees out of phase with its input voltage, a common uni-control means for simultaneously adjusting both of said biasing means, in a predetermined manner, the output of either amplifier being zero when the other is a maximum, and means for combining the outputs of said amplifiers to secure a resultant output voltage of any desired phase difference with respect to the input voltage of said apparatus.

7. A phase shifting apparatus comprising a source of waves to be shifted over a given phase range, a pair of electron discharge devices each having an input and an output circuit, means for applying said waves to the input and output circuits of one of said devices with a reference phase and to the input and output circuits of the other of said devices with a different phase, separate non-frequency selective feedback circuits coupled between the input and output circuits of each of said devices, separate means for varying the mutual conductance of each device, and a common non-frequency selective load circuit for combining the resultant of the waves developed in the output circuits of said devices.

8. An arrangement according to claim 7 wherein said phase difference is substantially electrical degrees and means for adjusting said varying means simultaneously to effect a predetermined phase change pattern.

9. Apparatus for phase shifting waves from a given source over a given phase range, comprising a pair of electron discharge devices each having an input and an output circuit, means for applying said Waves to the input and output circuits of one of said devices with a reference phase, means for applying said waves to the input and output circuits of the other of said devices with a different phase other than integral multiples of 90, individual feedback circuits coupled between the input and output circuits of each of said devices, separate means for varying the mutual conductance of each of said devices, and means for combining the resultant of the Waves developed in the output circuits of said devices.

EVERHARD H. B. BARTELINK.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,178,012 White Oct. 31, 1939 2,220,201 Bliss Nov. 5, 1940 2,231,955 Schrader Feb. 18, 1941 2,238,249 Crosby Apr. 15, 1941 2,261,356 Foster Nov. 4, 1941 2,284,083 Bond May 26, 1942 2,288,740 Peterson July 7, 1942 2,294,372 Barton Sept. 1, 1942 2,376,392 Shepherd May 22, 1945 2,388,769 Shaffer Nov. 13, 1945 

